WHILE WATCHING director Stanley Donen's latest film. Blame It on Rio, the viewers feel like tourists who have spent a day without suntan lotion under the scorching rays of Rio-completely burned. Unlike the cast, who blame Rio's sultry steaminess for their inane behavior, we can only blame co-writers Charles Peters and Larry Gelbart for their soap-opera like script and contrived plot.

The film centers around a holiday vacation, in which two middle-aged friends. Matthew (Michael Caine) and Victor (Joseph Bologna) escape to Rio to offset their mid-life crises with some warn weather adventure. When the movie opens, Victor is already in the midst of a divorce, while Matthew receives a rude awakening when packing with his wife Karen, (Valerie Harper) for Rio. Karen informs Matthew that he cannot put his snorkeling equipment in her suitcase because she has decided to go to Club Med to think their marriage over.

Victor and Matthew are accompanied by their teenaged daughters, Jennifer (Michelle Johnson) and Nicki (Demi Moore). While the foursome drive along the strip of beach upon arriving at Rio and notice sun bleached bodies cavorting on the sand, Victor asks "Maybe we should talk about 'boys." We see however, as the film progresses, that Victor's parental concerns do not extend any farther than the brief car ride. In fact by the end of the film, we begin to wonder who the children really are.

While Victor roams the beaches and cruises nightclubs. Matthew begins an affair with Jennifer, the adolescent. Gelbart and Stevens must have thought that Rio exudes an atmosphere that sparks improbable romances. How else could one explain the affair between the sheepish Matthew and the sultry Jennifer. Since no legitimate explanation can be gleaned from the script, we are forced to believe Jennifer's explanation, when she tells Nicki "I've always had a crush on your father."

Matthew himself seems equally unconvinced that he is actually having an affair with the 15 year old daughter of his best friend. "Last night never happened," he tells Jennifer the night after their moonlight encounter on the beach. "I know," Jennifer says, smiling smugly, "I was there." These vacuous lines do nothing to enforce the believability of the relationship.

Both Jennifer and Matthew, we are shown, have emotional holes in their daily lives, Jennifer's unstable family causes her to seek affection from the paternal Matthew, while Matthew reacts to his wife's rejection and the pangs of mid-life in-security. Jennifer is a young woman who simply makes him feel virile again. "You're not too old, and it's not too cold," she tells him as she pulls him into the ocean.

BUT IF THE WATER is not too cold, the acting is almost consistently so. Johnson, as the sultry Jennifer-older and more experienced than her 15 years-delivers her lines as if she were reading them from cue cards that were too far away. She seems uncomfortable in front of the camera, even while initiating her seduction of Matthew, Joseph Bologna, as her father, plays the part of an insensitive boor with excessive mannerisms and a loud voice. Michael Caine, in turn, seems constantly confused, as if he was just thrust in front of the camera and attempting to regain his composure. Caine, however, does the best he can and delivers the few comic moments in the film wonderfully. Finally, Demi Moore puts in the movie's most endearing performance as the disillusioned Nicki who sadly watches her friend Jennifer lead her father astray.

Gelbert and Peters attempt to incorporate serious issues into their plot ranging from divorce, to mid-life crises, to suicide, yet while they present them, they do not have any substantive messages or themes to relay. Instead, they seem to respond to them simply out of a sense of misplaced duty, just as stupidly as when Jennifer remembers to remove her retainer before rolling in the sand with Matthew.

The beauty of Rio and its pulsating population are perhaps the most spectacular features of the movie. As we witness an exquisite sunset, we begin to wonder how anyone could possibly blame Rio. It is far more inspiring and life like than both the film's plot and its characters.